13 March 2017

IPv4 to IPv6 without going through IPv5

We
are talking about IPv6 lately because we
are running out of IPv4 and we increasingly need more and more IPs
for the new area of Internet of Things (IoT). It's
a fact that the IP next generation (IPng) protocol and the IPv5
experimental protocol are not so well known by IT engineers but what
we should know is about the IPv6 protocol like addressing and
subnetting, stateful and stateless autoconfiguration, IPSec support,
the new anycast packets, transition mechanisms,
etc.

I
want to highlight transition mechanisms
used by main technology companies like
Akamai, Google or Cisco because, maybe, as a network engineers, we'll
have to participate or migrate IPv4 to IPv6 networks
in the future.

Dual
Stack: This is the most advisable way
to migrate from IPv4 to IPv6 because we can do it periodically and
progressively. However, all devices should support both protocols,
IPv4 and IPv6.

Dual-Stack transition mechanism

NAT64:
This is a transition mechanism based on Address
FamilyTranslation
(AFT), which is
a NAT technique similar to the traditional NAT for IPv4. In
addition, all devices should be behind a NAT64 router.

NAT64 transition mechanism

6to4
tunnel: This
is another method to connect two IPv6 worlds separated by IPv4,
where boundary routers make a 6to4 tunnel against each other. They
are going to use the prefix 2002::/16 where the IPv4 tunnel address
is identified inside the IPv6 domain.

Tunnel transition mechanism

ISATAP:
or Intra-Site Automatic Tunnel Addressing
Protocol is an
extension of the dual stack mechanism,
because it relies
on dual stack nodes to make
the migration, and it also uses tunnels.
However, the ISATAP mechanism is often criticized because it depends
on the DNS protocol to know the Potential Routers List (PRL). As a
result, a layer 3 protocol needs a higher layer protocol to work
properly, which is a violation of network design principles.

ISATAP transition mechanism

Next,
we can see an example of 6to4 tunnel transition mechanism along with
the network diagram and the configuration for Alcatel-Lucent
Omniswitch: